4.1 Crank in a 3.8 block?

[Hit Man X]

Is this a possible to do? Like sticking a 400 crank in a 350 block?

Full o' questions!

 

[unboostedV6]

Yes, it's identical to the turbo 3.8 crank. The stroke is the same, so there won't be any increase in displacement, but it's stronger than the N/A 3.8 crank. GB

 

[Turbo-Rich]

I read once that the odd-fire 3.8's crankshafts were stronger than even-fires. Don't know how true it is

 

[elk93001]

Another crankshaft question

I have seen racing crankshafts in the Performance Auto Warehouse (PAW) catalogs.

Are these crankshafts just as strong the hydraullically rolled fillet cranks on the turbo 231s and NA 252s?

What would be the downside?

 

[Hit Man X]

So, you'd have to use 4.1 rods to get some more displacement then? Anyone ever done this?

 

[b4black]

The 4.1's bore is larger than the 3.8, that's it. You need a 4.1 block and pisotns. Everything else is the same.


An odd-fire crank would be stronger becuase the rod journals aren't split. But the even-fire NA crank is fairly storng and the turbo crank is likely more crank than anybody here will ever need.

If you find the turbo crank isn't enough, you're probably are already shopping for a stage block for your 9 sec car.

 

[unboostedV6]

I'd like to add that bore, stroke, and the number of cylinders are the only things related to displacement. Rods have nothing to do with it. As far as practicality is concerned, there is not enough material or room in either the 3.8 or 4.1 production blocks to significantly increase displacement. Yes, odd fire cranks are stronger yet, but you'd have to acquire an odd fire distributer, and odd fire cam, an odd fire timing set, and odd fire rods to go with it. Like Rich mentioned, the N/A even fire cranks are plenty strong for most contributers to this board. Fred runs lots of boost, and I spin lots of RPM's, so we use turbo 3.8/4.1 cranks as insurance. Never had one fail. GB

 

[Turbo-Rich]

Originally posted by unboostedV6
Yes, odd fire cranks are stronger yet, but you'd have to acquire an odd fire distributer, and odd fire cam, an odd fire timing set, and odd fire rods to go with it

Hey
I never said I wanted one, lol.
I had just recently read an article where two 231's (one even-fire & one odd) were compared side by side to see which one made the most HP with the same turbo/tune/etc.
The results were that neither one made more HP than the other.
The conclusion was that the odd fire's crankshaft had proven to be stronger but they didn't go into why it was so as Rich did.